Method for securing a valve cap

ABSTRACT

A theft resistant valve cap including a liner adapted for threaded engagement with a standard pneumatic tire stem valve, a sleeve rotatably mounted with the liner to shroud it and an interlocking feature to selectively prevent axial displacement between the liner and the sleeve. The interlocking feature includes a screw threaded into an aperture in the sleeve, or other coupling device, and an annular channel on the liner, positioned to receive the screw. The annular channel has an upper surface, a lower surface and an inner surface disposed between the upper and lower surfaces. The screw is moved so that it extends into the channel resting proximate to the upper surface, but clear of both said lower and inner surfaces. The screw can be removed after the valve cap has been installed. In this fashion, the liner and the sleeve are in a fixed axial position with respect to each other; however, the rotatability of the sleeve with respect to the liner is maintained, preventing removal of the liner from the stem. The rotational movement of the sleeve prevents removing the liner and/or the sleeve from the valve stem.

This application is a Divisional of Ser. No. 09/151,186 filed Sep. 10,1998, U.S. Pat. No. 6,102,064.

TECHNICAL FIELD

The present invention pertains to the field of pneumatic valves.Specifically, the present invention pertains to an improved cap for usewith a standard pneumatic tire stem valve.

BACKGROUND OF THE INVENTION

Valve caps for standard pneumatic tire valves have traditionally beenemployed to protect the valve stem from degrading due to corrosioncaused by exposure to the environment. The traditional valve caps weretypically manufactured from inexpensive polymer-based materials. Assuch, they were relatively inexpensive and weren't aestheticallyappealing. A drawback with the traditional valve cap is that they wereeasily removed allowing access to the valve actuating member of thevalve stem so air could be released from the tire by unauthorizedpersons.

In recent years, designer caps have come into existence. One such cap isdescribed in U.S. Pat. No. Des. 306,420. The designer caps areaesthetically appealing to the average person and are much moreexpensive than the traditional valve caps. Typically, a single designervalve cap can cost several dollars. A major drawback with the designercaps is that they are easily removed from the valve stem. Similar to thetraditional valve caps, this allows unauthorized person to release airfrom the tire. More significant, however, it that easy removal raisesthe possibility that the cap would be stolen, due to its aestheticappeal. This is a major factor in dissuading purchasers from investingin designer caps. To reduce the probability of unauthorized removal,tamper resistant valve caps have been developed.

U.S. Pat. No. 5,630,687 discloses a prior art tamper resistant valve capthat includes a liner adapted for threaded engagement with a standardpneumatic tire stem valve, a sleeve rotatably mounted with the liner toshroud it and an interlocking feature to selectively prevent axialdisplacement between the liner and the sleeve. The interlocking featureincludes a screw threaded into an aperture in the sleeve, and an annularchannel on the liner, positioned to receive the screw. The annularchannel has an upper surface, a lower surface and an inner surfacedisposed between the upper and lower surfaces. The screw is moved sothat it extends into the channel resting proximate to the upper surface,but clear of both said lower and inner surfaces. In this fashion, theliner and the sleeve are in a fixed axial position with respect to eachother; however, the rotatability of the sleeve with respect to the lineris maintained, preventing removal of the liner from the stem. Therotational movement of the sleeve prevents removing the liner and/or thesleeve from the valve stem. While this valve cap provided superiorprotection against unauthorized removal of the same, it was subject todamage due to cross-threading of the liner onto the valve stem.

What is needed, therefore, is a theft resistant valve cap which has areduced probability of cross-threading during operation.

SUMMARY OF THE INVENTION

A valve cap includes a liner adapted for threaded engagement with astandard pneumatic tire valve stem, a sleeve rotatably mounted with theliner to shroud it and an interlocking feature to selectively preventrotational displacement between the liner and the sleeve. The linerincludes upper and lower portions with the upper portion including acircular disc supported above the lower portion by a shaft. Formed intothe circular disc are one or more recesses to facilitate deformation ofthe circular disc. Typically, both the shaft and the lower portion arecylindrical. The diameter of the shaft is much smaller than the diameterof either the upper and lower portions, defining an annular channel. Theannular channel has an upper surface, a lower surface and an innersurface disposed between the upper and lower surfaces. The interlockingfeature includes a screw threaded into an aperture in the sleeve, and anannular channel on the liner, positioned to receive the screw. Thesleeve has an inner surface defining a profile complementary to theprofile of the liner. To that end, the interior surface of the sleeveincludes an annular projection disposed proximate to a closed end,defining a bulwark. The bulwark is spaced apart from the closed end,defining two spaced apart chambers with a throughway extendingtherebetween. One of the chambers, disposed proximate to the closed endis adapted to receive the circular disc. The throughway, however, has adiameter which is slightly smaller than the diameter of the circulardisc. In this manner, the liner and the sleeve are insnapping-engagement. The interference fit between the bulwark and thecircular disc limits the axial displacement between the sleeve and theliner while maintaining rotational movement therebetween, therebypreventing removal of the liner from the stem. To remove the liner, and,therefore, the sleeve from the valve stem, the rotational position ofthe sleeve with respect to the liner is fixed. This is achieved bymoving the screw so that it extends into the channel and rests againstthe inner surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of the present invention in accord withthe preferred embodiment;

FIG. 2 shows the invention of FIG. 1 mounted onto a pneumatic valve stemof a standard automobile tire;

FIG. 3 is a perspective view of the threaded liner shown in FIGS. 1 and2 in accord with the present invention;

FIG. 4 is a cross sectional view of the liner shown above in FIG. 3,taken along lines 4—4;

FIG. 5 is a perspective view of the threaded liner shown in FIGS. 1 and2 in accord with an alternate embodiment of the present invention;

FIG. 6 is a cross sectional view of the liner shown above in FIG. 5,taken along lines 6—6;

FIG. 7 is a cross sectional view of a liner shown above in FIGS. 1 and 2in accord with a second alternate embodiment; and

FIGS. 8 and 9 show alternate embodiments of a key and locked used inaccord with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to both FIGS. 1 and 2, the present invention is shown asincluding a hollow liner 11, a hollow sleeve 13 and a reciprocatingmember 15, such as a screw. The liner 11 includes an upper portion 25, alower portion 27. The upper portion 25 is disc-shaped and supportedabove the lower portion 27 by a shaft 28. The upper portion 25, lowerportion 27 and the shaft 28 define an annular channel 31 having upper 31a and lower 31 b surfaces, as well as an inner surface 31 c extendingtherebetween. The lower portion 27 extends from the lower surface 31 b,terminating in an orifice 29. Formed into the circular disc are one ormore recesses 30, discussed more fully below.

The sleeve 13 has a closed end 17 and a sidewall 19 extending therefromterminating in an opening 21, as well as an interior surface 32. Theinterior surface 32 has a profile complementary to the profile of theliner 11. To that end, the interior surface 32 of the sleeve 13 includesan annular projection disposed proximate to the closed end 17, defininga bulwark 33. The bulwark 33 is spaced apart from the closed end 17,defining a cavity 35 having a varying diameter. The cavity includes twospaced-apart chambers 18 and 20 with a throughway 22 extendingtherebetween. The diameter of the throughway 22 is smaller than thediameter of the chambers 18 and 20. A threaded aperture 23 is formedinto the sleeve 13 to receive the reciprocating member 15. Preferably,the aperture 23 is formed into the portion of the sidewall 19 proximateto the bulwark 33. This provides a stronger and more durable area inwhich to support the reciprocating member 15, while minimizing thematerials necessary to construct the sleeve 13.

The opening 21 is shaped so that the liner 11 may pass therethrough andthe disc 25 may be disposed within one of the chambers 18 disposedproximate to the closed end 17. Preferably, the throughway 22 has adiameter which is slightly smaller than the diameter of the circulardisc 25. In this manner, the liner 11 and the sleeve 13 are insnapping-engagement upon the disc 25 being disposed within the chamber18. The chamber typically has a diameter slightly larger than the disc25. This allows limiting the axial displacement of the sleeve 13, withrespect to the liner 11, while maintaining rotational movementtherebetween. In this configuration, the closed end 17 of the sleeve 13covers the upper portion 25 of the liner 11, and the sidewall 19 extendsso as to completely cover the lower portion 27. The sidewall 19 may belonger or shorter than lower portion 27. However, it is preferred thatthe sidewall 19 be coextensive with the lower portion 27.

The liner 11 includes a plurality of inner threads 39 positioned to becomplementary to the threads 41 of a stem 43 of a pneumatic valve for astandard automobile tire 45. In a final resting position upon the stem43, the liner 11 provides the same advantages as a traditional valvecap. The sleeve 13 fits over the liner 11 and, with the aforementionedsnapping engagement freely rotates about axis 47 when the reciprocatingmember 15 does not engage the liner 11 to couple the liner 11 to thesleeve 13. This reduces the probability of unauthorized removal from thevalve stem 43.

The facilitates removal of the liner 11 and sleeve 13 from the stem 43by movement transverse to axis 47. Specifically, the reciprocatingmember 15 facilitates removal of the liner and, therefore the sleeve 13,from the stem 43 when the reciprocating member 15 wedges against theinner surface 31 c. In this manner, the angular position of the sleeve13 with respect to the liner 11 is fixed, thereby allowing the liner 11and the sleeve 13 to move as a single unit. Moving the sleeve 13 and theliner 11 as a single unit avoids separation of the liner 11 from thesleeve 13 after the assembly has been removed from the stem 43. In theretracted position, the reciprocating member 15 is spaced-apart from theinner surface 31 c allowing rotational movement of the sleeve 13 aboutaxis 47. It is preferred that the reciprocating member 15 not protrudefrom the outside surface when spaced-apart from the inner surface 31 cto prevent unauthorized removal of the same. Alternatively, thereciprocating member may be removed from the valve cap entirely afterthe valve cap has been installed on the valve stem. For example, thereciprocating member can be a screw with a knurled knob, thus allowingthe reciprocating member to be tightened against the inner surface forinstallation or removal of the valve cap by use of the fingers, notneeding an additional tool, such as an Allen key or wrench. A singlereciprocating member could then be used to install or remove all valvecaps in a set (e.g. all 4 on a car).

Typically, the liner 11 is manufactured from an inexpensive and softpolymer-based compound and protects the stem 43 from environmentalhazards and may include a rubber O-ring 60, to that end. Specifically,the liner 11 was typically formed from polyurethane or other softcompound which provided the flexibility required to couple to the sleeve13. However, a problem was encountered in that the inner threads 39 ofthe liner 11 were easily damaged due to cross-threading of the same whenbeing attached to a valve stem 43. To avoid the aforementionedcross-threading, the liner 11 is manufactured from a harder materialsuch as a compound of acrylonitrile butadiene and styrene, commonlyreferred to as ABS, an acetal resin, such as the type manufactured byDuPont™ under the trade name DELRIN™, or other suitable material.

Referring to FIGS. 2, 3 and 4, difficulties arose when changing thematerial from which the liner 11 was formed. More specifically, the disc25 would shear when passing through throughway 22. This would render theliner 11 inoperable. To avoid the shearing problem, a recess 30 wasformed into the upper surface of the disc 25. To provide the disc 25with the flexibility necessary to allow the same to deform sufficientlyso as to pass through the throughway 22 and expand to the original shapeupon entering chamber 18, the recess 30 is formed therein. The recess 30has an arcuate shape and extends across a diameter of the disc 25, butcould have a different shape, such as a square notch or dovetail.

Referring to FIGS. 5 and 6, in another embodiment, a pair ofintersecting channels 130 are formed into the disc 125 of the liner 111.The channels 130 extend across a diameter of the disc transversely toone another. Although it is not necessary, the periphery 125 a of thedisc 125 may be tapered to facilitate insertion of the same in tochamber 18. Finally, the disc 225 may be provided with flexibility bymanufacturing the same with a void 230 therein, shown in FIG. 7.

FIG. 8 shows a detailed view of a reciprocating member 715 having acavity 717 typically configured to fit an Allen wrench 719. It ispreferred to utilize this configuration in the present invention toreduce costs. Nonetheless, added security may be provided by havingkeyed-cavity, shown in FIG. 9. The cavity includes a plurality of sides721 which are arbitrarily arranged. The sides may be either flat 723 orround 725. The reciprocating member is turned via a key 727. The key 727has sides 729 that have a shape complimentary to the shape of the sides721 of the cavity. In this manner, the reciprocating member may beuniquely associated with a key member, further reducing the possibilitythat the sleeve and liner may be removed for the tire valve-stem.

What is claimed is:
 1. A method for securing a valve cap of the typehaving an internally threaded liner and a sleeve, said methodcomprising: covering said liner with said sleeve, with said linerextending from a first end, along a longitudinal axis, terminating in asecond end, disposed opposite to said first end; deforming one of saidfirst and second ends to form an interference fit between said liner andsaid sleeve.
 2. The method as recited in claim 1 further includingselectively limiting longitudinal movement between said liner and saidsleeve.
 3. The method as recited in claim 1 wherein said one of saidfirst and second ends defines a top portion having opposed regions, withdeforming one of said first and second ends including moving saidopposed regions in opposite directions.
 4. The method as recited inclaim 1 wherein said first end has a cross-sectional area associatedtherewith and includes a recess, defining a plurality of flexibleregions, with deforming one of said first and second ends furtherincludes moving said plurality of flexible regions to reduce saidcross-sectional area.
 5. The method as recited in claim 1 wherein saidone of said first and second ends has a cross-sectional area associatedtherewith and includes a plurality of recesses formed therein, defininga plurality of flexible regions, with deforming one of said first andsecond ends further includes moving said plurality of flexible regionsto reduce said cross-sectional area.
 6. The method as recited in claim 1wherein said sleeve includes first and second chambers, with athroughway extending therebetween, with a cross-section of saidthroughway being less than a cross-section of said first and secondchambers, with deforming one of said first and second ends furtherincludes reducing a cross-sectional area of said first end to passthrough said throughway so as to be disposed within one of said firstand second chambers, forming an interference fit therewith.
 7. Themethod as recited in claim 1 further including selectively limitingrotational movement between said liner and said sleeve by reciprocatinga member between said liner and said sleeve.
 8. The method as recited inclaim 1 wherein said liner includes an outer surface defining an annularchannel and further including selectively limiting rotational movementbetween said liner and said sleeve by reciprocating a member toselectively extend between said sleeve and said annular channel.
 9. Amethod for securing a valve cap of the type having an internallythreaded liner with flexible regions disposed at a first end thereof,and a sleeve, said method comprising: covering said liner with saidsleeve, with said liner extending from said first end, along alongitudinal axis, terminating in a second end, disposed opposite tosaid first end; deforming said first end by moving said flexible regionsto form an interference fit between said liner and said sleeve; andselectively limiting movement between said liner and said sleeve whilemaintaining rotational movement therebetween.
 10. The method as recitedin claim 9 wherein deforming said first end further includes moving saidflexible regions in opposite directions to reduce a cross-sectional areaassociated with said first end.
 11. The method as recited in claim 9wherein said sleeve includes first and second chambers, with athroughway extending therebetween, with a cross-section of saidthroughway being less than a cross-section of said first and secondchambers, with deforming said first further includes reducing across-sectional area of said first end to pass through said throughwayso as to be disposed within one of said first and second chambers,forming an interference fit therewith.
 12. The method as recited inclaim 9 further including selectively limiting rotational movementbetween said liner and said sleeve.
 13. The method as recited in claim 9further including selectively limiting rotational movement between saidliner and said sleeve by reciprocating a member between said liner andsaid sleeve.
 14. The method as recited in claim 9 wherein said linerincludes an outer surface defining an annular channel and furtherincluding selectively limiting rotational movement between said linerand said sleeve by reciprocating a member to selectively extend betweensaid sleeve and said annular channel.
 15. The method for securing avalve cap of the type having an internally threaded liner havingflexible regions disposed at a first end thereof, and a sleeve, saidmethod comprising: covering said liner with said sleeve, with said linerextending from said first end, along a longitudinal axis, terminating ina second end, disposed opposite to said first end; deforming said firstend by moving said flexible regions to form an interference fit betweensaid liner and said sleeve; selectively limiting longitudinal movementbetween said liner and said sleeve; and selectively limiting rotationalmovement between said liner and said sleeve.
 16. The method as recitedin claim 15 wherein deforming said first end further includes movingsaid flexible regions in opposite directions to reduce a cross-sectionalarea associated with said first end.
 17. The method as recited in claim16 wherein said sleeve includes first and second chambers, with athroughway extending therebetween, with a cross-section of saidthroughway being less than a cross-section of said first and secondchambers, with deforming said first further includes reducing across-sectional area of said first end to pass through said throughwayso as to be disposed within one of said first and second chambers,forming an interference fit therewith.
 18. The method as recited inclaim 17 wherein selectively limiting rotational movement between saidliner and said sleeve further includes reciprocating a member betweensaid liner and said sleeve to extend therebetween.
 19. The method asrecited in claim 17 wherein said liner includes an outer surfacedefining an annular channel wherein selectively limiting rotationalmovement between said liner further includes reciprocating a member toselectively extend between said sleeve and said annular channel.
 20. Themethod as recited in claim 18 wherein said member is hollow having aninterior side and further including shaping said sides, defining a keyedstructure.